Prior known devices for modifying the operation of a valve in an internal combustion engine can be seen in U.S. Pat. No. 4,917,058, No. 4,836,162, No. 4,771,742, No. 4,770,060, No. 4,724,809, No. 4,723,515, No. 4,469,056, No. 4,261,307 and No. 2,934,052. All of these known devices require complex rocker arm or cam follower configurations, and/or complex cam shaft configurations. For example, U.S. Pat. No. 4,723,515 discloses three separate cam surfaces for each valve, which greatly increases the cost of manufacturing the cam shaft. The same is true for U.S. Pat. No. 4,469,056 which also discloses three cam surfaces for each valve, and also discloses a complex mechanical structure for following the three cam surfaces and actuating the valve. U.S. Pat. No. 2,934,052 discloses a simpler mechanism for actuating the valve, however this mechanism operates as a simple switch mechanism to change between a first position in which the valve operating means is actuated responsive to rotation of the first cam and a second position in which the valve operating means is actuated responsive to rotation of a second cam.
These prior known devices suffer from disadvantages associated with high manufacturing cost of the components required to practice the invention and lack of adjustability, having been designed for only one or two pre-set configurations.